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Ravenheat CSI 85AT boiler tripping problem?

Ravenheat condensing combi boiler CSI 85AT fault?

My 1.5 year old boiler has developed a random & intermittent tripping fault, in both modes of heating (i.e. CH & DHW). With the remote programmer calling for heat or the hot taps turned on, it often runs for a few minutes OK and then trips out and restarts after about 5 seconds the starting purge/fire cycle. Sometimes it will trip out before ignition occurs, but it usually processes through the cycle and the flames are good and NG blue. It sometimes continues running for maybe 5 minutes prior to tripping, so the intervals vary. Occasionally on DHW mode it will not fire for quite a few minutes so one gets a good supply of cold water!

I have checked the air pressure switch tubing to see if there was a blockage or leak, and also that the switch operates by blowing the tube/sucking and it seems to be free & operable. I have checked that both the CH & DHW thermistors are working and are giving sensible readings. The fan is free to rotate and runs OK. The overheat thermostat does not seem to be operating when the boiler eventually gets the system up to temperature & the red LED has not been illuminated. The boiler gas pressure was set by the CORGI commissioning engineer and has not been altered. The water pressure is set to 1 bar + and the low water pressure stat does not appear to be incorrect.

Any ideas what to check next? I suppose it could be a weak connection on the PCB but tapping it did not cause a trip!

Brian Mallalieu
January 2007
Thanks all, for the really helpful threads . the tripping problem on my csi85 was cured by switching the pilot unit

Neil W
October 2014
Hi my boiler only gives hot water ,Its only 5 month old.Press button [manuel] red light comes on but no heating , does anybody no whats wrong ?

steve from radcliffe manchester.
February 2014
I know nothing about gas boilers but my pressure gauge goes to 3 bar and the pipe leading outside looks like an over flow pipe is leaking. How do I relieve the pressure to get the bar reading down

October 2013
can anyone help me with my Ravenheat about a year ago it started playing up i could only get hot water by having the c,h on if i put the switch on just water it would not fire up just trip off now a year on the c,h fires up for about 5 minutes then stops after about another 2 minutes it will fire up again then cut out again.. when the c,h is on as soon as i turn the hot water tap on it trips i have had the boiler for about 5 years the longest it has worked with out playing up is 1 year i have replaced one of the sensors should i replace both... thanks

February 2012
Check the primary thermistor and the two wires connected to it. If you have a mk2 version (two lights on the front) then the primary thermistor provides overheat protection as well as control function and frost protection. If it is failing, it will cause the boiler to short cycle On off etc etc. forget messing around with testing the resistance, just replace it. (around £14 for a genuine one and as little as £4 for a copy one

chris m
August 2011
My Ravenheat boiler is just out of Guarentee (typical). It works fine for hot water, and the centeral heating if it is on 24/7. But if the heating is on a timer, it will ramdomly trip out, about one a week and the red light will flash. It will trip when the timer is just switching on. It also, like a lot of posts listed will fire up the centeral heating for about 5-10 seconds then cut out, then re fire, etc. What could be the problem?? Reading the many posts it could be a number of things with these crappy units!


July 2011
The manual for the CSI 85 does not mention that the spark electrode also doubles as a sensor. A tiny signal from the electrode when heated by a lit boiler "tells" the boiler's brain that the gas is lit. It's a bit like the effect of an old style thermocouple. The signal is first sent to the condensate trap. If the condensate liquid level reaches the earth wire at the top of the trap, indicating a blockage, the tiny signal won't get back to the "brain". It goes to earth and shut down is ordered. The typical sequence is, spark ignition, pilot lit, main burner lit, shut down. This cycle is repeated. You don't need an actual blockage for the signal to be earthed and cause shut down. The condensate trap gets mucky and the tiny signal can be earthed by nothing more than dirt on the contacts. You can check the trap by removing either of the wires attached by phillips screw to the top of the trap. Make sure the wires can't contact earth while you test. If the boiler operates normally with the sensor wires off, you've found the problem or more correctly one of two problems. The first is the condensate drain is blocked and if so clear it and re-install the wiring. Bear in mind that any damp connecting the earth and sensor wire will cause a fault, so you have to make sure when re-fitting the condensate trap that all is clean and completely dry. The second is that the signal is being earthed by dirt, moisture etc and that's a simple clean up job. So, following the signal path to the condensate trap we've checked the trap itself as above. If the fault is still there when we have the condensate trap wires disconnected you need to check the pilot and/or pilot injector. This is because the signal originates at the ignition electrode, heated by the pilot. The pilot becomes hot, the electrode being heated sends the tiny heat-generated signal on its way to the brain. The signal is intercepted at the condensate trap which we've already checked because that's the easier one to deal with. You'd need to be qualified to dismantle the pilot injector assembly. It's a simple job to replace an injector but it's not legal to do so. However, it may be just deposits blocking the pilot flame which can be brushed away. Any way you can achieve a decent pilot flame will solve the problem if that's where the fault originates. I should add here that what we're trying to get is a good electrical signal back to the brain. Even if we have a clean functioning condensate trap and good pilot flame, the cable at the ignition electrode can become loose so check the connections on the cable very carefully and the cable itself in case wear is causing it to earth the signal.
There is also something completely different (but not at all funny) that can cause problems. There is a gasket at the back of the boiler where the condensate hose comes directly out of the back of the condenser. There is one where the gas supply enters boiler body. There is also a small one where the gas pilot pipe and ignition wire enters the body. Check all of these and that the seal around the front boiler cover (the interior cover that is, not the white outer) is good. The pressure switch tends to fail but also when it's working fine broken gaskets are what it's looking for in the first place. Mostly the sensors break down when there's no fault but if there are holes in gaskets they really do need fixing. Try to get genuine replacement gaskets but FIREPROOF materials such as glass rope can be used to good effect, particularly on the big silicone gasket on the back (where the condensate hose connects to the condenser). That gasket in particular is prone to breakage and a little troublesome to replace, involving a fair amount of dismantling. It should be easy to replace but the metal spigot of the condenser which passes through the boiler body is often sitting on the bottom edge of the circular hole in the body. This is because of poor build quality. The substantial weight of the condenser sits on the gasket and presses it against the thin steel edge of the body, cutting it. If you have a problem in the pressure switch/gasket area you should be able to temporarily block any gasket leak to check where the problem might be, then you won't have to replace a gasket that you suspect which is actually ok.

June 2011
I have had Ravenheat CSI Primary for 7 years. Performs well. I have had two solvable problems. First, the Air Pressure Switch (APS), at top of the boiler, sometimes gets stuck. Symptoms are the boiler turns on electrically but does not fire up the burner. To resolve this, I sometimes have to bang the top right side of the boiler with my hand to dislodge the stuck switch. Couple of seconds later the burner comes on. I believe this is a well known fix for this boiler.

Second problem, now sorted as a result of reading this forum, thank you all, is the continuous tripping off of the burner. Symptoms, burner comes on for 5-10 seconds then cuts off, and couple of seconds later it ignites again and this cycle continues. Tried suggestion oiling the fan shaft, this did not resolve.

Turned boiler off. Disconnected the thin copper gas pipe feeding the pilot light. Carefully eased it out of the pilot assembly. On the tip of this pipe is a small cap which has two very very small pin holes, I found a small residue blocking these holes. (Looked like a couple of grains of sugar). Carefully flicked the residue away from the pin holes, so as not to imbed in them. Reassembled and up and running again. Thanks again, hope this helps others.

March 2011
Often the non ignition/fan issue is caused by the relays on the main board which are cheap and nasty and the contacts carbon up so they dont work, I have taken cover off and cleaned contacts they then work again, last one over a year and still going. However a better fix is this quality relay which will last years, get a local radio/tv shop to change them if your not experienced at fine pcb soldering. this is the one , mail order possible :
Also if no HW but CH still works fit a new diverter valve diaphragm ( they go in all combis about 3-4 yrs due to chlorine in water supply) half an hour max and running again. Alot of the problems with these and other combi boilers is that many so called engineers simply dont understand them and cant fault find, despite their protests to the contrary.

February 2011
Actually, it's a Silver Star. Sorry.

January 2011
Hi. I have a White Star with no CH/HW. Problems started after it was switched off for a week and when switched back on made a loud metallic banging noise. RH suggested pump failure so I removed it, but the mechanism seemed fine - it moved freely without excessive play - so I refitted it. I switched it back on but got the red flame failure light. After several attempts to restart it the light went from solid red to flashing red. After another couple of restarts the red light stayed out. So now I've got the green power light and the red timer light and nothing else but silence.
I've tried the banging method with no change.
It's Friday now so I can't phone RH until Monday, and it's bl***y cold in here! Can anyone help?

January 2011
Same cut-out fault as everyone else. I have had 2 boiler engineers out, not from Ravenheat as they are not doing callouts until April. They couldn't fix it. I have replaced sensors, ignition board, controller board, pressure switch and cleaned injector. Still not working! All I want to do now is get a designer from ravenheat, stand him/her against a wall and shoot them with a ball of their own Shite!! BIN YOUR BOILER IF CAN AFFORD A NEW ONE

Gerry Redford
January 2011
The best thing that could happen to these ravenheap
boilers is a trip to the local tip scrap metal skip, it does not matter how many times you have them repaired because time and again some other fault will occur regularly throughout its short lifespan I have had two of these junk apollo 13 excuses for central heating boilers & at long last thank God above some plumber down the pub reccomended a new glow worm 35 cxi which has now working like a good un,hot water for a change a luxury I have never had before!!!

jim townsley
January 2011
hello i had the same problem and i changed the two thermisters on mine 6 quid off ebay and they work a treat hope that helps

January 2011
Sling it mate. Ravenheat is the worst boiler on the planet. The design engineers should all be serving long prison sentences for crimes against humanity.How they ever managed to get any recognised body to certificate this rubbish beggars belief.
The components are all from Roys bodgit shop.
If the company had one shred of decency it would recall all these boilers and have them crushed.
PLease please please read the blogs before you buy any boiler. It is all there in black and white. The plumber who sold it to you and installed it should be doing a long stretch in the Siberian Goolag.

Harriott C
January 2011
why is my ravenheat boiler not tripping off on central heating, it can be switched on all day and it stays lit all day without tripping out., cheers

December 2010
I had a problem where the boiler was initially cycling, ie turning on then off again after a minute or two. Then one day it just wouldn't fire up. The pilot ignition spark could be heard, I could see the pilot light up but ..... and here's the clue.... It continued to spark!! I was told by an engineer that it needed a new PCB £200. Wasn't convinced so I took the front off the boiler, blew into the rubber tube to activate the pressure switch near the fan and noticed that the pilot only had a small flame.... not the 20mm as recomended by Ravenheat plus it was still sparking. I therefore dismantled the pilot injector, initialy tried cleaning it but then heated it to red hot with a blow torch, reassembled.... now bigger flame and hey presto it now works! I'm sure I'll eventually need a new injector..... but couldn't of been easier to fix!!

November 2010
We recently bought a second house and found that the owner had hidden all the evidence of significant damp under carpets and behind boxes and furniture. We had to do some significant work that meant that the heating system was left drained for 8 months. When I came to start it up again it wouldn't start, it would go through the start up sequence but the burner would not light and then the valve would close. I got a qualified gas boiler guy round, who firstly told me that the boiler was cheap sh*t from B&Q and then he spent a couple of hours on it and could not find the problem. Faced with the possibility of paying lots of money for another gasman or the cost of a new boiler I decided to take matter on myself. Going through fault finding in the manual and the internet threads I eliminated all the low cost possibilities one at a time and the boiler still wouldn't light. So in despiration I decided to do what the gasman did myself and dissassembled the pilot and ignitor assembly. When doing so, I noticed that the assembly had actually being installed incorrectly in the first place by the qualified technician and they had routed the ignitor cable around the outside of the sealing grommet (at bottom of burner assy) and they'd also put the pilot gas supply through the wrong hole of the grommet. So I rerouted both pipe and ignition wire and added some additional insulation to the ignition wire. Hey presto, the boiler started up the next time I turned it on. It appears that the electrode wiring had fretted and was shorting to the metal casing, giving the clicking sound but in the worng place.
The moral to this whole episode is that if you are going to stick it in the wrong hole, make sure it has rubber around or you'll find sparks will fly but there wont be any satisfaction. Also, think laterally, even professionals make mistakes, and that's not just GPs.

On The Fence
October 2010
Hello, I bought my ravenheat CSI 85AT 5 years ago and like most have had ongoing issues. Have had the usual fan issues which I like to think is working ok. My problem is now with the main burners, the boiler goes through the firing up sequence, fan on, pilot light on but stays in this mode until trips out. One thing I have noticed is that the sound from the fan is level where before it would 'hunt' before firing, normally on the second go ?
I had a replacement fan which I have installed but with the same results.
Have replaced the pilot lighter and cleaned the nozzles.

Any thoughts would be greatly appreciated as I am without hot water (again!)
thanks Kevin

October 2010
We have had problems with our Ravenheat CSI 85AT almost since it was fitted 3 years ago. (Many of the internal joints were leaking when the boiler was fitted. We replaced a 20 year old Worcester Heatslave, which had given us no problems but was underpowered after extending.
Within a couple of months, the fan failed. The bearing had disintegrated to dust.
I contacted Ravenheat, who sent out a young girl to inspect the boiler. She admitted she had no gas or heating qualifications - then tried to say it was my fault, as I had taken the fan out to check it. I have been a heating engineer for 40 years, so that didn't go down well with me. Ravenheat have refused to come out again or offer any help.
Now boiler trips out all the time, or won't fire up at all. Currently no heating or hot water. Got a new thermistor to fit, so will see what happens.
We do have a fault that no one else seems to have - the heating will switch itself on (though its turned off on the controls), usually in the middle of the night!
Just feel like ripping it out and trying to find something reliable.
Despite all my years in the business, I still can't get it to work reliably - must be the worst boiler ever made.

George, Northumberland
March 2010
My daughter has just bought a house which has a Ravenheat CSI-85T fitted. The house has been empty since Sep 2009 and she's decorating prior to moving in. When we turned on the gas and elec in Feb 2010 the boiler wouldnt fire. Happened to be a boiler engineer working in the same road and he had a look at it - checked the gas was all ok - couldnt get it going at all. Charged £40! Whenever we visited the house I try it to see if it works. On about 3 occasions the pilot lights, then the main burner came on. CH just starts to get warm when boiler trips and red indicator light comes on. After that it wont work again ie switch off elec, switch back on, the pilot burner comes on but no main burner then the red indicator light comes on. Had another combi boiler specialist look at it. He 'serviced' everything but couldnt get it to work. decided it was almost cetainly the circuit board and gave us a quote for £185 plus vat for the part alone ie not fitted. Reckons the boiler is a real crap model and rather than spend good money after bad recommends a new boiler - about £1300 fitted! He reckons if he fits a new board it will almost certainly go again in a short space of time. Daughter now in a complete dilemna - spend £180 plus; spend £1300 on what the last guy calls a decent make; or try someone else. This morning I went into the house and switched it on. Pilot started, main burner fired and radiators actually started to warm up. Then after about 3 or 4 mins it tripped, red light came on. Switch off elec then switched back on again many times. In all cases pilot comes on , no main burner then it trips. So what would people recommend, please? And if there's a Ravenheat Samaritan somewhere in or close to Manchester M22 Dane Rd/Sale who would like to try to crack it please let me know.

March 2010
Oh another annoyance with this s**t boiler is the condensing unit. This is made out of a very cheap casting metal muckite. During one of boiler hissy fits last year, it started leaking badly.
I took it out, opened it up and discovered that it was over three quarters blocked. This accounted for the excessive knocking and slow radiator performance which I was blaming on poor pipework and the hot water Zone valve not shutting off completely!
Many many hours later, with some good quality car gasket sealer, I had it cleaned, unclogged, reinstalled and leak free.
But for something which behaves like a sieve it would nice if was easier to access!

January 2010
Yesterday my Ravenheat CSI Stopped working. Again.

It is the fault mentioned most in this thread firing up the pilot light but not the main burner.

This is not a solution I would recommend any sane person follows as it is extremely dangerous!

In a desperate bid to get some heat out of it. I turned the boiler off at the mains. Took the PCB out of the plastic housing. I then made a hole in the top of the relay that controls the main burner, when pushed down it fires the main burner. Reconnected the PCB ensuring that I could safely get to the relay and that there was no chance of the PCB touching anything else that might cause a short.

This enabled me to fire up the main burner. This worked fine until the unit tripped out having not detected the pilot light. Turned the boiler off then on, pushed relay contact down and repeated this many times. Then suddenly, as if by magic, it started working all by its self!


January 2010
With this style of condensing boiler they use the spark-sensing electrode return voltage (milli volts generated when heated in the pilot flame) to confirm pilot light as an input to the ignition control board. When this return voltage is lost, the ICB shuts the main gas valve and try’s to relight. The relighting sequence may be instant or may take 3, 4 times or trigger no light fault light after a number of failures.
This returning cable is linked to the top of the condensation trap to further monitor for a trap blockage. In the event of trap blockage high level condinsate provides an earth path rendering return voltage to the ICB Zero Volts forcing above sequence. Remembering that this is a milli volts return signal easily lost, I have seen a dirty residue in the top of the Condensation trap providing an earth path. To trouble shoot whether this simple signal is giving you problems it is easier to remove the potential earth path, ie disconnect the spark-sensing electrode return wire from the top of the trap ( will ensure that no earth can fault occur). This wire must continue on to the ICB to give the signal. Restart boiler and monitor to see if fault has been eliminated. This Boiler fault is not explained very well in the manual or mentioned in the trouble shooting flow chart, you have to read between the lines and understand how the pilot light is confirmed you can see that this simple fault can send you looking up lots of blind alleys.
Cleaning the trap is difficult so I have simply left off and await the day that a slug slithers up the outside condensation pipe and the blockage causes a small leak as a sign that it is blocked.

January 2010
I am having similiar problems with my Ravenheat 85 it was doing the same thing as far as coming on was concerned and the HW would only get hot when the CH was running, then it started to start and stop when it felt like it and now that the weather has turned it decieded it was going to pack up, I now have no redlight, green is on but the boiler does not fire at all.
Anyone with any suggestions (apart from bin it)

January 2010
Having had extensive difficulties with my Ravenheat boiler, I eventually tried going down the route of replacing the thermistor. I replaced the one situated on the flow pipe and it cost only £6 of an Ebay seller.
The boiler is now working a treat and this came as a last attempt before investing about £800 on a new one! Fingers crossed it will stay working.

January 2010
I had exactly the problem described in the thread yesterday - refer to Mr Pilot Fixers answer Jan 2009 - this is the solution for the specific problem described, ie blocked pilot nozzle closing off the gas valve. Note the part no is 5012096 - though dont replace it - take the pilot burner with nozzle off and heat it to red heat with a blowtorch - this cleans all the carbon deposits off the nozzle and clears out the holes (there are two). Worked perfectly first time on reassembly. Cost of repair - £0.00. So thanks Mr PF for that. Note flue fan problems as referred to elsewhere in the thread present different symptoms, including red light on / lockout. (I've had that one too). What next I wonder??

Martin H
December 2009
problem with the boiler other than its rubbish is not the sensors but the wires prone to loose connection to sensor,s or gas valve pcb has dry joint on pcb

December 2009
Hi I had the same problem with the boiler tripping out. Check ebay for sensors. I just got two for £12 the pair. As for the 3 in one trick, it works fine for a while but i bought some molyslip( Most autoshops), normally used to lube car engines, instead of the 3 in 1 and, touch hairy wood,no problems since with the fan anyway. Still trip occasionally. Any clues

J Harpum
November 2009
My boiler is has similar faults to Those listed. After changing the Pressure swith, checking the fan speed. Trying a new PCB (Which turned out ot be faulty) Ravenheat now tell us the pilot jet blocks very easily. Stopping reducing the flow of gas. A little heat on the pilot will tes this. All you need to do is change the pilot jet.
This was prooven by our plumber applying heat to the pilot whilst blowing in the pressure switch, to fool the system into thinking it is sealed. Seems to be a common problem

Dave Leeds
October 2009
David from Watford......many many many thanks for you 3 in 1 oil answer !!!
My boiler kept firing up for 10 - 15 seconds then cutting out....before reigniting again. After spending £50 on sensors etc & hours pulling my hair out......I found your solution !!!! I followed it step by step & to my amazement it worked first time !!!! I owe you a few pints mate !!!! Many thanks

July 2009
allways try the c/h dhw sensor (thermistor) first, if your boiler does work at all (if power light is on) its a sensor that is on the flow pipe with yellow wires coming off it to the control board. You can pick them up from a partcenter for about £17+. If you try that first it could save you a lot of money, my mother in law had this problem and called out a gas engineer and he told them that it was the motherboard and it cost them £181 and when it was fitted no differance, i recently completed my gas safe qualification and had a look and saw it was the thermistor, if you have a multi meter then just stick that on the thermistor. I hope this is handy for you and saves you a bit of money if this is the case.

June 2009
Thank you Geoff from Leeds and David from Watford. Had the same problem, boiler would start but after around 30 seconds the red warning light would come on.
After reading your posts, i decided to have a go. Took off the front cover started the boiler the fan was turning but not very fast?? So i stopped the boiler and thought i may aswell have a little fiddle with the fan anyway before i look elsware for information, so i rotated it cw and ccw and restarted the boiler after it went through its start up procedure the fan started, but this time a lot noisier and i could tell it was running at full speed. ( i nearly crapped myself as the noise made me jump and i wasn't very confident about playing with the boiler) but the gas did not light. After reading another post i realised about the pressure valve and secured the main cover with two screws. After restarting the boiler it worked and has been fine since, but i am going to clean it out soon and re-oil the shaft.
Thank you all for posting your suggestions as i am sure this has saved me a packet.

Mark Leeds
March 2009
i have hot water but no heating have changed overheat sensor and c/h sensor to no avail. please help

February 2009
Most tripping problems on Ravenheat boilers relate to the Honeywell Control valve and the pilot supply.
The Valve ref 0008VAL06006/0 is intelligent and monitors the gas flow to the pilot. If the flow is low it shuts down the pilot and main valves. This results in the boiler continuously firing up and shutting down.
The usual problem is a partly blocked pilot nozzle. answer replace nozzle ref 502096.
Cleaning out the old (0.27mm bore) nozzle is very difficult and can do more damage than good.
Any tripping problems always check the pilot supply.

Mr. Pilot Fixer
January 2009
You won't believe this! I had the FAN PCB replaced last year for constant banging and failure to light. I have just had another tripping problem with the Ravenheat model 85 AT. Earlier in the day, the Heating/Water would run for about 30 secs and then stall. Later in the day, the flame would ignite and diminish almost as quickly. The boiler would cycle through its sequence and startup but fail instantly for both heating and water. I thought that it may be a thermistor or the fan control board or something more serious!....
The actual problem was a minute hole in a rubber pipe, leading from the flue to the air pressure switch! Got it replaced! Its fixed now but I am sure that I have years of problems to look forward to!

January 2009
i've just brought a csi primary aaa rated boiled its been fitted but it will not fire up the fan and pump or working but it just does not want to light up i went back to b&q and there not willing to help.. can any body me please??? please i'm stuck many thanks anton

January 2009

December 2008
ravenheat boilers are rubbish

November 2008
Running water for for 3 or 4 min's ok & then it runs cold.
Replace Sensor on RHS (Green Connector) . -
Fixed my problem
Although it's worth buying 2 just in case to replace the 2nd
Temperature sensor on the heat - Exchanger if the above
does not resolve.

RAVENHEAT Part no: 0007TER05005/0

November 2008
Changed the CH sensor/thermistor as advised by Debby and it solved the tripping out problem for me. This has been an issue I've had for ages, so I'm well chuffed. Thanks Debby!

Russell S
October 2008
fan speed is a real problem with boilers /rpm indicator required ,get it sorted boiler manufacturers

nick p
October 2008
Perhaps a different type of boiler but a Ravenheat combi non the less. I had hot water but no heat, tried fiddling with pressure switch and replacing thermistor, no joy.Looking at hte wiring diagram gave me the idea to by-pass the timer by altering the wiring and hey presto the boiler fires on both hot water and central heating. New clock to source now but at least I can manually overide the timing system on my 840ET combi boiler. The connections sre on 3&5 of the timer , 3&4 are normally closed do i simply swapped connections (after reading the diagram again) heat heat heat. Nowt like it , .

saved myself a few quid
October 2008
I've just had the same problem, the boiler would run but not light, and after about 30 seconds would trip and the flame out light would come on, so after reading David from Watford's post i went to investigate. firstly i took the front panel off and switched on the boiler, the one thats the one under the cosmetic white one. anyway i noticed that the fan was not turning this is the one on the flue, so i turned it with a screwdriver a few time while the boiler is turned on, it started to turn slowly at first then faster until the boiler lit, (ha,ha i thought, cracked this) yeh right, it stopped and the light came on agian (bummer) so out with the WD40 few quick squirts and bingo back in bussines,(yeh you guessed) it it stopped as soon as the heat from the flue got to it, so took out all the screws and removed the fan pull it towards you may need a bit of a nudge with a screw driver, stripped it down, the fan is a pressed fit onto the shaft so a little persuation is needed to get it to move but it does, take care to keep the thrust washers in the correct order for re-assembly, clean everything up, use some high melting point grease just a smear on the bushes and shaft re-assemble re-fit switch on and see if it works. mine did and so saved me a bundle as a mate of mine had a new fan fitted £300 rip off. hope this helps someone cheers Dave

Geoff Leeds
April 2008
Have the same problem although it has developed after four years. I have replaced the clock, main board, ignition board and gas valve (not new but from an identical and fully operational bioler). Mine started its problems with a failed fan then a year after fan replacement it would only fire up if cold but could run for several hours, as long as it does not idle. The flow chart says to check for 230 volts at 'ML' ; but ML is not on the schematic. I am sure that the problem lies in a sensor or some value that is being sent to the main board as the low voltages on Modureg (connected by two purple wires to the gas valve from the main board) are different when the readings are taken on working and non working versions.
I have now cleaned the corroded contacts on the Sensors/Thermistors; no joy. I have compared the resistance on a working boiler and non-working boiler and the non-working shows 3 or 4 times higher values. The working boiler shows a drop of two thirds of its value after working for 2 minutes. I will buy and fit new sensors (drain and refill boiler). What I have observed so far is that the terms C.H & D.H.W. are confusing when considering the sensors. More useful is primary and secondary as the C.H. sensor when disconnected stops the boiler after the pump starts to run and it serves the two circuits (it is in use even when only D.H.W. is called for. Both circuits will not work if the C.H. sensor is sending out the wrong reading.
When the C.H. is turned on; checks are run; the pump starts; the fan starts; air is blown into the air-valve (if the pipe is not kinked); if the condensate trap is not blocked (and sending the signal to earth) the pilot light igniter will start to click; if the pilot light ignites the main burners should light-up very quickly.

David Eden
January 2008
Have the same problem although it has developed after four years. I have replaced the clock, main board, ignition board and gas valve (not new but from an identical and fully operational bioler). Mine started its problems with a failed fan then a year after fan replacement it would only fire up if cold but could run for several hours, as long as it does not idle. The flow chart says to check for 230 volts at 'ML' ; but ML is not on the schematic. I am sure that the problem lies in a sensor or some value that is being sent to the main board as the low voltages on Modureg (connected by two purple wires to the gas valve from the main board) are different when the readings are taken on working and non working versions.

David Eden
January 2008
Per info from me before, on the Ravenheat CSI 85T - Overheat thermostat came and was fitted. Boiler worked - for a short time. Engineer therefore called out and was baffled at first but by process of elimination calculated it was the thermister and the boiler (not the system) had to be drained off to get to it as it is a 'wet' sensor apparently. No charge was being read from the thermister and a new one (with charge reading) was installed - luckily our friendly Engineer with years of experience is aware that these come in all shapes and sizes and varying charge levels etc., and carried what we needed on the van. Boiler is now working and purring like a kitten at a cost (including part) of £70. Apparently, the part (the Thermister) is around £17+.

Hope this helps anyone with the same problems.

December 2007
Mine is doing same too. If you read the user guide, faults point to overheat thermostat. Mine is now three years old and it started 'tripping out' a few months ago and need to 'cool down' before it will work again.

We did replace the pump after 6 months, but were advised by Engineer that this could go at any time.

What is annoying though is that on same boiler, a few months after I bought it, Ravenheat increased their warranty to three years on this boiler, so I believe!

I have not contacted Ravenheat yet, but if it is a global fault, i.e. affecting all models then the owners of those models should maybe group together to get a resolve of the problem from Ravenheat.

We have an overheat thermostat due for delivery, so will see what happens. Interesting about the Fan though!

December 2007
Mine is the same age and started doing this occassionally straight after install and has gradually worsened. I have now been waiting 1.5 years for a service call which they firstly refused to make and then said they would charge me for if it happened to be working when they arrived. Now it is out of warrenty they are ignoring me......
I have heard it is a common fault on these boilers at this time-if I get anywhere with Ravenheat I will let you know

September 2007
I believe I had a similar type of problem with the same boiler type but mine would not light without continually resetting the switch over and over again. The process would commence on either cycle but the boiled would trip out and the red light would come on. I tried all the usual suggestions (no small expense !!) until I finally decided that I seriously needed to understand how the thing works. What I discovered was that the fan, although it was working, it wasn't rotating fast enough when cold to increase the air pressure within the chamber, this acts like a sealed unit with the steel cover in place, and trips the air pressure switch (top right) which turns on the gas and lights the boiler. I found I could demonstrate this by removing the rubber tube from the flue ring (inside top centre), turning on the boiler, blowing gently into the tube and the boiler would light every time, as soon as you stop blowing the flame ignition stops. The cure was simple and cheap, I got my trusty tin of 3-in-one oil from the garage, turned off the power to the boiler and oiled the shaft of the fan in-situ, I found that a bendy straw fitted snuggly over the spout of the oil can and gave me good access to the fan shaft, do not flood it though, a little oil goes along way. I then ran the boiler without lighting it to let the oil do its work. Fingers crossed, the fan now whizzes round and the boiler lights when it should. I can only conclude that initially, by continually resetting the boiler the fan shaft must have warmed up sufficiently to spin fast enough to operate the pressure switch. Might sound crazy, but it worked for me and the tin of oil is cheaper than all those uneccessary replacement parts I ended up buying. Hope this helps.

David from Watford
April 2007
hi did you find an answer mine is doing exactly the same

April 2007


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